Checking the air: Stations put science in Tri-State pollution alerts

JASON CLARK / Courier & Press
Roberta Shawhan checks on equipment at one of the air quality monitoring stations in Evansville recently. The stations measure amounts of fine particle pollution, ozone, nitrates and sulfates in the air. The measurements show if the area's air meets EPA standards.

Shawhan explains how the data collected by the area stations is recorded on various computers. She said it takes nine hours to check the stations.

Imagine a circle about 60 miles across.

Now, imagine having to predict what the air will be like above that circle on any given day. Welcome to Joanne Alexandrovich's job.

Alexandrovich is one of many forecasters and researchers across the state and the country who issue air quality alerts and forecast levels of pollution, specifically ozone and fine particle pollution — also called "PM 2.5."

Alexandrovich, an ozone officer for the Vanderburgh Department of Health, helps monitor the air in a 15-county area that includes the cities of Evansville, Henderson, Ky., and Owensboro, Ky.

"It's not all that easy to get it perfect," Alexandrovich said of forecasting air quality for the region, "even though that's what we strive for."

From the speaker phone in Alexandrovich's office booms the voice of Steve Sherman, the lead forecaster for the Indiana Department of Environmental Management. He and Alexandrovich were having a teleconference with two state officials to forecast the area's air quality.

"It's a little bit questionable, but I think ozone will be in the moderate (range) this afternoon," he said. "Particulate matter is so low right now, tomorrow will be good and that should carry into Wednesday."

For real-time data on local air quality, log on to http://www.airnow.gov. Select Indiana from the drop down box and click on Evansville.

Alexandrovich said one of the reasons predicting air quality isn't an exact science is because air alert days are dictated by weather patterns. Strong winds and cooler temperatures lead to cleaner air. Low or no winds, sunlight and high temperatures have the opposite effect.

After a few minutes, the conference call wraps up, although Alexandrovich spent nearly two hours researching and prepping for it.

"When we agree, it's a pretty short meeting," she said.

When they don't agree, the group stays on the phone, weighing the pros and cons of issuing an air quality alert. They tend to be overly cautious.

In 2007, there were 44 alert days for either ozone or particulates, but only 15 days when levels actually went over the Environmental Protection Agency's standard. So far this year, there have been no alert days.

"Some people think that we know exactly what it will be the next day, but that's not it at all," Alexandrovich said.

In fact, the group is working off a range of forecasts. One predicts high, while another predicts low. If that range falls across the line between air quality that's moderate and air quality that's unsafe, well, that's why some meetings last longer than others.

Across town, Roberta Shawhan also is at work, beginning one of her twice weekly drives to the air quality monitoring stations around the area.

Shawhan said it takes nine hours to check all 10 monitoring stations. The work usually is split between two people.

The monitoring stations measure the amounts of particulates, ozone, nitrates and sulfates in the air, she said. The measurements show whether the area is meeting standards set by the EPA.

Vanderburgh County currently is in nonattainment for short-term exposure to fine particle pollution.

Inside the station, glass tubes reach across the ceiling and down the back wall, funneling outside air through a series of filters. Monitors set up at eye level display the results.

Although the current fine particle pollution readings are below the EPA standard, a single day's worth of data isn't enough to take the county out of nonattainment status.

Dona Bergman, director of the Evansville EPA, said that to allow for weather fluctuations, the readings are averaged over a three-year period.

Dramatic reductions in emissions from nearby coal-fired power plants have helped lower levels of air pollution in Vanderburgh County substantially since 2004, Bergman said. But power plants remain a large source of pollution for the area.

Although there are no coal-fired power plants in Vanderburgh County, 17 are located within the area Alexandrovich helps monitor — including one of the largest in the world, the Gibson Generating Station in Gibson County, Ind. Two more are planned for the area as well.

John Blair, president of environmental group Valley Watch, said part of the problem is that Midwestern coal is naturally high in sulfur — a precursor for fine particle pollution.

Data provided by the Vanderburgh County Department of Health showed that in Gibson County, an estimated 200,000 tons of sulfur dioxide was emitted during 2006.

By comparison, the latest federal data — from 2000 — showed Indiana as a whole had slightly more than 870,000 tons of sulfur dioxide emissions.

"It's quite obvious to anybody that looks at the numbers that the majority of the pollution in this area comes from the power plants," Bergman said. "They've spent literally billions of dollars to reduce emissions, and they'll likely spend billions more."

Nationally, the trend has been to toughen pollution standards as more research is done about the impact on human health and the environment.